What Is Cobalt Hydroxide?
Cobalt hydroxide, known in forms as cobalt (II) hydroxide and cobalt (III) hydroxide, is primarily utilized in its cobalt (II) state. It is classified under various safety and health regulations, indicating the need for careful handling and use of protective equipment due to its potential health risks.
Uses of Cobalt Hydroxide
Cobalt hydroxide is integral in producing cobalt metal, cathode materials for nickel-hydrogen batteries, metallic soaps, paint desiccants, and as a catalyst. It improves electrode conductivity in batteries by transforming into cobalt oxyhydroxide upon initial charging.
Properties of Cobalt Hydroxide
1. Cobalt Hydroxide (II)
This light reddish powder is stable under normal conditions but can oxidize in air or with oxidants to cobalt hydroxide (III). It’s insoluble in water but dissolves in aqueous ammonia and ammonium salt solutions, posing irritation risks and requiring airtight storage.
2. Cobalt Hydroxide (III)
As a dark brown powder, cobalt (III) hydroxide is insoluble in water, ethanol, nitric acid, sulfuric acid, and aqueous ammonia.
Structure of Cobalt Hydroxide
1. Cobalt Hydroxide (II)
With the formula Co(OH)2, this compound features a hexagonal cadmium hydroxide-type crystal structure, with a density of 3.597 g/cm3.
2. Cobalt Hydroxide (III)
Typically existing as Co2O3･nH2O, it predominantly occurs in a hydrated form with variable water content.
Other Information on Cobalt Hydroxide
1. Cobalt Hydroxide (II) Production
Produced by reacting an aqueous cobalt salt solution with sodium hydroxide in the presence of glucose, it initially forms a blue precipitate that stabilizes to light red over time.
2. Reaction of Cobalt Hydroxide (II)
As an amphoteric compound, cobalt (II) hydroxide dissolves in acids and alkalis, with its solubility product being approximately 1.3 x 10-15.
3. Reaction of Cobalt Hydroxide (III)
Cobalt (III) hydroxide forms when a cobalt (III) salt solution reacts with sodium hydroxide and dehydrates to a monohydrate at 100°C, eventually producing chlorine when dissolved in hydrochloric acid.